There are two main types of Integrated Circuit (IC) packages: lead frame packages and laminate frame packages.
In lead frame packages, the conductors consist of leads that have been produced from a single copper alloy strip by stamping or etching. The conductors are thick enough to impart mechanical rigidity to the package components during assembly. Typically, the lead frame package has leads that contact the printed circuit board (PCB) on which the IC package is located, at its periphery either along two opposite sides or on all four sides. One type of lead frame package is a Quad Flat Package (QFP), which may be a Metric QFP (MQFP) or a Thin QFP (TQFP).
Laminate packages, on the other hand, contain a PCB. The conductors in this case consist of traces etched in copper foil bonded to a reinforced polymer substrate. Laminate packages have several layers of conductors and planes with the inter-layer connection provided by through-hole plated vias. Laminate packages normally have an area array of leads. One very common (and commercially important) type of laminate package is the Ball Grid Array (BGA) package. In this case, the leads consist of balls of solder on the underside of the IC package. Another type of laminate package is a Chip Sized Package (CSP).
An integrated circuit package must be tested before the package is assembled to a higher assembly. Packages are typically tested at component level by placing the package into a test socket.
Many types of test sockets are known and each test socket is typically designed to test a particular type of package, be it a lead frame or a laminate package.